Turn to notice spur (4)
I believe the answer is:
goad
'spur' is the definition.
(synonyms)
'turn to notice' is the wordplay.
'turn' becomes 'go' (a person's move in a board game).
'to notice' becomes 'ad' (both can mean an advertisement).
'go'+'ad'='GOAD'
(Other definitions for goad that I've seen before include "Spur or stimulate" , "A dog to urge on" , "Act as stimulus - with pointed stick?" , "Prompt" , "Spur, urge on" .)