Well-timed strength needed to grasp large fish (9)
I believe the answer is:
fortunate
'well-timed' is the definition.
(thesaurus)
'to grasp large fish' is the wordplay.
'to' becomes 'forte' (I am not sure about this - if you are sure you should believe this answer much more).
'grasp' means one lot of letters goes inside another.
'large fish' becomes 'tuna' (I've seen this before).
'forte' going around 'tuna' is 'FORTUNATE'.
'strength needed' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for fortunate that I've seen before include "Blessed with good luck" , "Lucky" .)