Natural pull, upwards (3)
I believe the answer is:
gut
'natural' is the definition.
(as in a gut feeling)
'pull upwards' is the wordplay.
'pull' becomes 'tug' (tug is a kind of pull).
'upwards' shows that the letters should be reversed in order.
'tug' in reverse letter order is 'GUT'.
(Other definitions for gut that I've seen before include "Cologne's good" , "good for Goering" , "Food processor" , "Stomach, maw" , "The stuff of a violin string" .)