Paint terrapins another way? No sweat! (14)
I believe the answer is:
antiperspirant
'no sweat' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'paint terrapins another way?' is the wordplay.
'another way?' indicates anagramming the letters (I've seen 'another way' mean this).
'paint'+'terrapins'='paintterrapins'
'paintterrapins' with letters rearranged gives 'ANTIPERSPIRANT'.
Can you help me to learn more?
(Another definition for antiperspirant that I've seen is " spray in the bathroom?".)