It can produce regenerated tail, no trouble (4)
I believe the answer is:
newt
'it can' is the definition.
The definition suggests a singular noun which matches the answer.
'regenerated tail no trouble' is the wordplay.
'regenerated' becomes 'new'.
'no' is a deletion indicator.
'trouble' becomes 'ail' (synonyms).
'tail' with 'ail' removed is 't'.
'new'+'t'='NEWT'
'produce' acts as a link.
(Other definitions for newt that I've seen before include "Small, lizard-like amphibian" , "Ask" , "Garden-pond amphibian" , "Semiaquatic amphibian" , "Amphibious creature" .)