Bowler's developing with age, experience at either end, and hard work (5,6)
I believe the answer is:
elbow grease
'hard work' is the definition.
(synonyms)
'bowler's developing with age experience' is the wordplay.
'developing with' is an anagram indicator (letters developed into a new form).
'experience' becomes 'e' (this could be a standard abbreviation which I don't know about).
'bowlers' with its letters mixed up with 'age' can make 'elbowgreas'.
'elbowgreas'+'e'='ELBOW-GREASE'
'at either end and' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for elbow grease that I've seen before include "Vigorous physical labour involving hard rubbing" , "Hard physical effort" , "Hard rubbing (colloq.)" , "Vigorous physical effort" , "Hard physical work (informal)" .)