Though of unexcitable nature, I had to clap wildly! (6)
I believe the answer is:
placid
'though of unexcitable nature' is the definition.
I can't judge whether this definition defines the answer.
'i had to clap wildly' is the wordplay.
'i had' becomes 'I'd' (contraction).
'to' means one lot of letters go next to another (I've seen this in other clues).
'wildly' indicates an anagram.
'clap' with letters rearranged gives 'plac'.
'id' put after 'plac' is 'PLACID'.
Can you help me to learn more?
(Other definitions for placid that I've seen before include "Serene - unruffled" , "Tranquil, unruffled" , "or is it an American one?" , "Calm, phlegmatic" , "Tranquil, even-tempered" .)