Indication in letter read aloud? (3)
I believe the answer is:
cue
'indication' is the definition.
(thesaurus)
'letter read aloud?' is the wordplay.
'letter' becomes 'q'.
'read aloud?' shows a homophone (sound like) (I've seen 'read aloud' mean this).
'q' is a homophone of 'CUE'.
'in' is the link.
(Other definitions for cue that I've seen before include "Prompt; reminder" , "hit ball, in a way" , "Signal (to actor)" , "Signal to players" , "Tapering stick used by snooker player" .)