It helps to make poetry and rhyme tremendously effective (5)
I believe the answer is:
metre
'it helps to make poetry' is the definition.
The definition suggests a singular noun which matches the answer.
'rhyme tremendously effective' is the wordplay.
'METRE' is hidden in amongst the letters.
But, I am uncertain how the hidden word is indicated.
'and' is the link.
Can you help me to learn more?
(Other definitions for metre that I've seen before include "three and a bit of a fourth" , "39.37 inches" , "Yard is smaller than this" , "Basic unit of length" , "Approx. thirty nine point three seven inches" .)