Ale without head that is uncanny (5)
I believe the answer is:
eerie
'uncanny' is the definition.
(I've seen this in another clue)
'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' (short for Latin 'id est', 'that is').
'beer' with its first letter removed is 'eer'.
'eer'+'ie'='EERIE'
(Other definitions for eerie that I've seen before include "Oddly frightening" , "Weird, uncanny" , "Bloodcurdling" , "Strange, unusual" , "Spooky, creepy" .)