Very angry, i.e. with rodent inside (5)
I believe the answer is:
irate
'very angry' is the definition.
(I've seen this in another clue)
'i e with rodent inside' is the wordplay.
'with' is a charade indicator (letters next to each other).
'rodent' becomes 'rat' (rat is a kind of rodent).
'inside' is an insertion indicator.
'i'+'e'='ie'
'ie' enclosing 'rat' is 'IRATE'.
(Other definitions for irate that I've seen before include "Infuriated" , "ranting" , "Extremely angry" , "Narked" , "Extremely cross" .)