Ale without head that is weird (5)
I believe the answer is:
eerie
'weird' is the definition.
(both can mean strange or unsettling)
'ale without head that is' is the wordplay.
'ale' becomes 'beer' (I've seen this before).
'without head' means to remove the first letter.
'that is' becomes 'ie' (abbreviation for id est, 'that is' in Latin).
'beer' with its first letter removed is 'eer'.
'eer'+'ie'='EERIE'
(Other definitions for eerie that I've seen before include "Spooky, supernatural" , "Spectral" , "Sinister" , "Weird and disturbing" , "Uncannily strange" .)