One who’s experienced love, great LSD trips (3,6)
I believe the answer is:
old stager
'one who's experienced' is the definition.
'love great lsd trips' is the wordplay.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'trips' indicates an anagram.
'great'+'lsd'='greatlsd'
'greatlsd' anagrammed gives 'ldstager'.
'o'+'ldstager'='OLD STAGER'
(Other definitions for old stager that I've seen before include "One who's experienced a lot" , "expert" , "veteran" , "senior citizen" .)