Develops shade, not tails (5)
I believe the answer is:
heads
'not tails' is the definition.
The definition and answer can be both to do with motion as well as being verbs in their -s form.
Perhaps they are linked in a way I don't understand?
'develops shade' is the wordplay.
'develops' indicates anagramming the letters.
'shade' anagrammed gives 'HEADS'.
Can you help me to learn more?
(Other definitions for heads that I've seen before include "Goes for" , "Chiefs" , "Leaders" , "School principals" , "Coin-tossing call" .)