A good number of massive intermediate age (around a few Gyr) metal-poor star clusters in the Magellanic Clouds (MCs) show extended main-sequence turn-off, that can not be explained by photometric errors or stellar binarity. Kron 3 is one such cluster, located to the west of the main body of the Small Magellanic Cloud which has a range of estimated radius as well as age. In this study, we have demonstrated the power of UVIT- HST- Gaia-VISTA combination to study star clusters in the MCs. We take advantage of the resolution of the HST in the central region of the cluster and the coverage of Gaia and VISTA for outer region, to combine with the UVIT data, where we have used photometry in the NUV band with a large spatial coverage. We have estimated the radius of the cluster Kron 3 as 2.0 arcmin from the UVIT and Gaia data. For the first time, we report the identification of NUV bright red clump (RC) stars and the extension of RC stars over two magnitudes both in colour and magnitude axis in NUV vs (NUV - optical) CMD. We find that the extension of RC is an intrinsic property of the cluster and not due to field star contamination. With the help of theoretical isochrones, we suggest that Kron 3 exhibits multiple stellar population with a possible age range of 6-8 Gyr and a metallicity range of [Fe/H] = -2.0 to -1.0. Theoretical spectral fits to spectral energy distribution of RC stars confirm the metallicity spread among the RC stars. The temperature of RC stars falls in a very small range of 5000-5500 K, indicating that these are indeed RC stars. We suggest that a spectroscopic study of RC stars can throw more light on the metallicity spread present in the cluster.