Pick-me-up is too nice to drop endings (5)
I believe the answer is:
tonic
'pick-me-up' is the definition.
(I've seen this before)
'too nice to drop endings' is the wordplay.
I cannot really understand how this works, but
'to' is within the answer.
This may be the basis of clue (or it may be nonsense).
'is' is the link.
Can you help me to learn more?
(Other definitions for tonic that I've seen before include "Important note" , "Quinine drink; keynote" , "requirement for invigoration?" , "something invigorating" , "fizz" .)