When life begins to be a bit like a stronghold? (5)
I believe the answer is:
forty
'when life begins' is the definition.
(proverbially, life begins at 40)
'a bit like a stronghold?' is the wordplay.
I cannot quite see how this works, but
'like' could be 'y' ('y' can be similar in meaning to 'like') and 'y' is located in the answer.
'stronghold?' could be 'fort' (I've seen this before) and 'fort' is found within the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'to be' acts as a link.
(Other definitions for forty that I've seen before include "When life begins" , "Two-score" , "-- winks, a short sleep" , "number of penitential days" , "Two score" .)