Hard work and energy, with erratic bowler's age (5-6)
I believe the answer is:
elbow grease
'hard work' is the definition.
(synonyms)
'energy with erratic bowler's age' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mc2).
'with' is a charade indicator (letters next to each other).
'erratic' indicates an anagram.
'bowlers'+'age'='bowlersage'
'bowlersage' anagrammed gives 'lbowgrease'.
'e'+'lbowgrease'='ELBOW-GREASE'
'and' acts as a link.
(Other definitions for elbow grease that I've seen before include "Hard physical effort" , "Vigorous physical effort" , "Vigorous physical labour involving hard rubbing" , "Hard rubbing (colloq.)" , "Hard physical work (informal)" .)