Hiding in Heidelberg I met a returning refugee (6)
I believe the answer is:
emigre
'refugee' is the definition.
(I've seen this before)
'hiding in heidelberg i met a returning' is the wordplay.
'hiding' says the answer is hidden in the clue.
'a returning' is a reversal indicator.
'ergime' is hidden within 'in heidelberg i met'.
'ergime' reversed gives 'EMIGRE'.
(Other definitions for emigre that I've seen before include "One leaving country for political reasons" , "One living abroad for political reasons" , "Someone leaving the country for good" , "person coming from Russia without love, perhaps" , "One leaving their nation" .)