Very pissed, breaking the clock (6)
I believe the answer is:
speedo
'the clock' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see an association between them that I can't see?
'very pissed breaking' is the wordplay.
'very' becomes 'so' (I've seen this in other clues).
'pissed' becomes 'peed' ('pee' can be a synonym of 'piss').
'breaking' indicates putting letters inside.
'so' going around 'peed' is 'SPEEDO'.
Can you help me to learn more?
(Other definitions for speedo that I've seen before include "reading from this" , "Make for swimmers" , "Mph indicator" , "Trademark swimming briefs" , "Dashboard instrument (abbr)" .)