Thanks German for sticker (3)
I believe the answer is:
tag
'sticker' is the definition.
(tag is a kind of sticker)
'thanks german' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'german' becomes 'g' (abbreviation).
'ta'+'g'='TAG'
'for' acts as a link.
(Other definitions for tag that I've seen before include "Children's chasing game" , "Refrain" , "Small label" , "stock quotation" , "Tie-on label" .)