Stick the head out again (6)
I believe the answer is:
adhere
'stick' is the definition.
('adhere' can be a synonym of 'stick')
'the head out again' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'again' becomes 're'.
'head' with letters rearranged gives 'adhe'.
'adhe'+'re'='ADHERE'
(Other definitions for adhere that I've seen before include "Stick to, cling" , "paste" , "Stick to or continue faithful" , "Remain attached" , "Stick to, remain loyal" .)