Learn to let loose, with time, becoming indulgent (8)
I believe the answer is:
tolerant
'indulgent' is the definition.
(thesaurus)
'learn to let loose with time' is the wordplay.
'let loose' is an anagram indicator.
'with' is a charade indicator (letters next to each other).
'time' becomes 't' (**).
'learn'+'to'='learnto'
'learnto' anagrammed gives 'olerant'.
'olerant' after 't' is 'TOLERANT'.
'becoming' acts as a link.
(Other definitions for tolerant that I've seen before include "Allowing carte blanche" , "Patient, forbearing" , "Accepting of others' ways" , "Easy-going" , "Rattle on (anag)" .)