Dog — the one we have — sweats (7)
I believe the answer is:
labours
'sweats' is the definition.
The definition and answer can be both acts as well as being plural nouns.
Maybe you can see a link between them that I can't see?
'dog the one we' is the wordplay.
'dog' becomes 'lab' (short for labrador).
'the one we' becomes 'ours' (I can't explain this - if you can you should believe this answer much more).
'lab'+'ours'='LABOURS'
'have' acts as a link.
Can you help me to learn more?
(Other definitions for labours that I've seen before include "Toils" , "Some work" , "Works hard and makes great efforts" , "Shakespeare: 'Love's . . . . . . . Lost'" , "Hercules underwent 12 of them" .)