Nothing actually to wear? I'd buy a T-shirt, possibly (8,4)
I believe the answer is:
birthday suit
'nothing actually to wear?' is the definition.
I can't tell whether this defines the answer.
'i'd buy a t-shirt possibly' is the wordplay.
'possibly' indicates anagramming the letters.
'id'+'buy'+'a'+'t'+'shirt'='idbuyatshirt'
'idbuyatshirt' anagrammed gives 'BIRTHDAY SUIT'.
Can you help me to learn more?
(Other definitions for birthday suit that I've seen before include "Nothing to wear?" , "State of total nakedness" , "Invisible outfit?" , "Invisible attire?" , "Invisible threads?" .)