I start relishing a single drop shimmering (10)
I believe the answer is:
iridescent
'shimmering' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I don't see?
'i start relishing a single drop' is the wordplay.
'start' indicates taking the first letters.
'a single' becomes 'I' (one).
'drop' becomes 'descent' (I've seen this in another clue).
The initial letter of 'relishing' is 'r'.
'i'+'r'+'i'+'descent'='IRIDESCENT'
Can you help me to learn more?
(Other definitions for iridescent that I've seen before include "Like a rainbow" , "Glittering with changing colours" , "changing colour" , "shimmering with colour" , "Showing luminous colours" .)