Beer spilt on the first hat (5)
I believe the answer is:
beret
'hat' is the definition.
(I've seen this before)
'beer spilt on the first' is the wordplay.
'spilt' indicates an anagram.
'on' is a charade indicator (letters next to each other).
'the first' becomes 't' (1st letter of 'the').
'beer' anagrammed gives 'bere'.
'bere'+'t'='BERET'
(Other definitions for beret that I've seen before include "Felt hat" , "French-style cap" , "Soft peak-less kind of cap" , "Flattish felt cap" , "Cap with no brim" .)