He turned a blind eye when it suited him (6)
I believe the answer is:
nelson
'him' is the definition.
'he turned a blind eye when it suited' is the wordplay.
I cannot quite see how this works, but
'he' could be 'nels' and 'nels' is located in the answer.
'when' could be 'on' (I've seen this in other clues) and 'on' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for nelson that I've seen before include "mariner with dodgy vision" , "Victorious flag officer" , "... famous admiral" , "One-eyed English admiral seen on pillar" , "Admiral; wrestling hold" .)