Long to possess a strong yellow protective garment (8)
I believe the answer is:
pinafore
'protective garment' is the definition.
(I've seen this before)
'long to possess a strong yellow' is the wordplay.
'long' becomes 'pine' (synonyms).
'to possess' is an insertion indicator.
'strong' becomes 'f' (musical symbol for 'forte', 'strong' in Italian).
'yellow' becomes 'or' (heraldic term).
'a'+'f'+'or'='afor'
'pine' placed around 'afor' is 'PINAFORE'.
(Other definitions for pinafore that I've seen before include "It protects female worker" , "Apron-like garment" , "'HMS - - ' G & S" , "Protective gear" , "Protective kitchen wear" .)