React badly, getting very small amount (5)
I believe the answer is:
trace
'very small amount' is the definition.
(I've seen this before)
'react badly' is the wordplay.
'badly' indicates anagramming the letters (letters in the wrong order).
'react' with letters rearranged gives 'TRACE'.
'getting' is the link.
(Other definitions for trace that I've seen before include "Barely detectable amount" , "Vestige, hint" , "Seek out" , "Find by investigation" , "Describe, small quantity" .)