Sat on extremely noncompliant capybara? (6)
I believe the answer is:
rodent
'capybara?' is the definition.
(capybara is a kind of rodent)
'sat on extremely noncompliant' is the wordplay.
'sat on' becomes 'rode' (as in sitting on a horse).
'extremely' means to remove the middle letters (only the extremes of the word are used).
'noncompliant' with its centre taken out is 'nt'.
'rode'+'nt'='RODENT'
(Other definitions for rodent that I've seen before include "Placental mammal having a single pair of incisor, 'gnawing', teeth" , "Eg, mouse or rat" , "Rat perhaps" , "Nibbler" , "A rat, for instance" .)