When retired, ponder being puzzled (7)
I believe the answer is:
bemused
'being puzzled' is the definition.
(being bemused is being puzzled or confused)
'when retired ponder' is the wordplay.
I cannot quite understand how this works, but
'when' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
'ponder' could be 'muse' (synonyms) and 'muse' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for bemused that I've seen before include "In the course of puzzling" , "Puzzled" , "Stupefied" , "Dazed" , "Perplexed, bewildered" .)