Coach rat in dancing (5)
I believe the answer is:
train
'coach' is the definition.
(both can mean to instruct a sportsperson)
'rat in dancing' is the wordplay.
'dancing' indicates an anagram.
'rat'+'in'='ratin'
'ratin' anagrammed gives 'TRAIN'.
(Other definitions for train that I've seen before include "Railway service" , "Teach (person) a skill" , "Means of transport or long tail on dress" , "held up in union action?" , "Locomotive and coaches" .)