Sauce, when cold, goes in sort of boat (7)
I believe the answer is:
tabasco
'sauce' is the definition.
(Tabasco sauce is an example)
'when cold goes in sort of boat' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'cold' becomes 'c' (eg on taps).
'goes in' is an insertion indicator.
'sort of' indicates anagramming the letters.
'as'+'c'='asc'
'boat' anagrammed gives 'tabo'.
'asc' going into 'tabo' is 'TABASCO'.
(Other definitions for tabasco that I've seen before include "ASBO Act (anag) - hot stuff!" , "Red pepper sauce" , "A hot spicy sauce" , "condiment?" , "Mexican state; pungent sauce" .)