He has to do something dramatic (5)
I believe the answer is:
actor
'he' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'has to do something dramatic' is the wordplay.
'has' becomes 'or' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'to' says to put letters next to each other (I've seen this in other clues).
'do something dramatic' becomes 'act' (I've seen this in another clue).
'or' put after 'act' is 'ACTOR'.
Can you help me to learn more?
(Other definitions for actor that I've seen before include "Gielgud, say" , "One taking part" , "eg Anthony Hopkins" , "Performer in drama" , "Dramatic artist" .)