Henry interrupts hysterically merry poet (6)
I believe the answer is:
rhymer
'poet' is the definition.
(I've seen this in another clue)
'henry interrupts hysterically merry' is the wordplay.
I cannot quite understand how this works, but
'henry' could be 'h' (symbol for the unit of electrical inductance) and 'h' is present in the answer.
an anagram of 'merry' is 'rymer' which is present in the left over letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for rhymer that I've seen before include "similar sound writer" , "Composer of poetry" , "Thomas of Erceldoune" , "16 dn of poems" , "Poet" .)