Think the notice outside made you laugh (6)
I believe the answer is:
amused
'made you laugh' is the definition.
The answer and definition can be both to do with communicating as well as being past participle verbs.
Perhaps you can see a link between them that I can't see?
'think the notice outside' is the wordplay.
'think' becomes 'muse' (to muse on something is to think about it).
'the notice' becomes 'ad' (both can mean an advertisement).
'outside' indicates putting letters inside.
'muse' inserted into 'ad' is 'AMUSED'.
Can you help me to learn more?
(Other definitions for amused that I've seen before include "Kept someone entertained" , "Queen Victoria wasn't!" , "Pleasantly occupied" , "Mildly entertained by Medusa" , "Provoked mirth in" .)