Second small beverage source of pleasure inside plant (5,3)
I believe the answer is:
sweet pea
'second small beverage source' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'pleasure inside plant' is the wordplay.
'pleasure inside' becomes 'sweet' (I can't justify this - if you can you should believe this answer much more).
'plant' becomes 'pea' (pea plant is a kind of plant).
'sweet'+'pea'='SWEET PEA'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for sweet pea that I've seen before include "Fragrant bloom" , "Celestial source of fluctuating radio waves" , "Climbing garden plant with pastel flowers" , "Climbing plant with fragrant flowers" , "A wee pest on fragrant climbing plant" .)