Offer to be third man in true love drama (9)
I believe the answer is:
volunteer
'offer' is the definition.
(I know that offer can be written as volunteer)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for volunteer that I've seen before include "Willing (or unpaid) worker" , "Offer one's services" , "Offer freely to do something" , "One offering to perform unasked" , "person working for free, perhaps" .)