Arms gave test clean away (9)
I believe the answer is:
tentacles
'arms' is the definition.
Although both the answer and definition are plural nouns, I don't see how one could define the other.
'test clean away' is the wordplay.
'away' indicates anagramming the letters (letters move away from their original places).
'test'+'clean'='testclean'
'testclean' with letters rearranged gives 'TENTACLES'.
'gave' is the link.
Can you help me to learn more?
(Other definitions for tentacles that I've seen before include "Feelers" , "Octopus parts" , "... but the octopus has eight" , "With these, the octopus takes a grip" , "Flexible organs on the head of some animals" .)