Silent thanks for tic returning (5)
I believe the answer is:
tacit
'silent' is the definition.
('tacit' can be a synonym of 'silent')
'thanks for tic returning' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'for' says to put letters next to each other.
'returning' is a reversal indicator.
'tic' written backwards gives 'cit'.
'ta'+'cit'='TACIT'
(Other definitions for tacit that I've seen before include "Understood, not spoken or played" , "Implied but not directly expressed" , "Implied -- inferred" , "Implied or understood, not put into words" , "Understood without being directly expressed" .)