Look at fish caught by the German in retirement (6)
I believe the answer is:
regard
'look at' is the definition.
(regarding is a kind of looking at)
'fish caught by the german in retirement' is the wordplay.
'fish' becomes 'gar' (gar is a kind of fish).
'caught by' is an insertion indicator.
'the german' becomes 'der' ('the' in German).
'in retirement' shows that the letters should be reversed in order (retire can mean to go back or backwards).
'der' back-to-front is 'red'.
'gar' inserted within 'red' is 'REGARD'.
(Other definitions for regard that I've seen before include "Consider; gaze at" , "given respect" , "Relation to" , "Judge" , "Look - respect" .)