Annoy one redhead at the King's Head (3)
I believe the answer is:
irk
'annoy' is the definition.
(I've seen this before)
'one redhead at the king's head' is the wordplay.
'one' becomes 'i' (Roman numeral).
'redhead' becomes 'r' (the head letter of red).
'at' means one lot of letters go next to another.
'head' says to take the initial letters.
The first letter of 'kings' is 'k'.
'i'+'r'+'k'='IRK'
(Other definitions for irk that I've seen before include "Wind up" , "cause annoyance" , "Severely annoy" , "Get at" , "Annoy in quirky way" .)