Signify agreement and finally remove swelling (4)
I believe the answer is:
node
'swelling' is the definition.
(thesaurus)
'signify agreement and finally remove' is the wordplay.
'signify agreement' becomes 'nod' (I've seen this before).
'and' says to put letters next to each other.
'finally' indicates one should take the final letters.
The last letter of 'remove' is 'e'.
'nod'+'e'='NODE'
(Other definitions for node that I've seen before include "Natural swelling of part of a plant or animal" , "Done to a small lump" , "Done (anag.); a knot" , "Point of branching in a network" , "Knob or lump" .)