A tiller reworked to be exact (7)
I believe the answer is:
literal
'be exact' is the definition.
('literal' can be similar in meaning to 'exact')
'a tiller reworked' is the wordplay.
'reworked' is an anagram indicator.
'a'+'tiller'='atiller'
'atiller' anagrammed gives 'LITERAL'.
'to' acts as a link.
(Other definitions for literal that I've seen before include "All tire (anag.)" , "Following the exact meaning" , "Word-for-word" , "Actual" , "Precise" .)