Adolescent golfer's starting-point: hack with energy (7)
I believe the answer is:
teenage
'adolescent' is the definition.
(I've seen this before)
'golfer's starting-point hack with energy' is the wordplay.
'golfer's starting point' becomes 'tee' (I've seen this in another clue).
'hack' becomes 'nag' (synonyms).
'with' says to put letters next to each other.
'energy' becomes 'e' (physics symbol as in E=mca).
'tee'+'nag'+'e'='TEENAGE'
(Other definitions for teenage that I've seen before include "Like one thirteen-nineteen years old" , "Tea gene (anag.)" , "Thirteen to nineteen" , "Suitable for years 13-19" , "of seven difficult years" .)