Disrobe, turning red, sun beginning to scorch (7)
I believe the answer is:
undress
'disrobe' is the definition.
(I know that disrobe can be written as undress)
'turning red sun beginning to scorch' is the wordplay.
'turning' indicates an anagram.
'beginning to' says to take the initial letters.
The first letter of 'scorch' is 's'.
'red'+'sun'='redsun'
'redsun' with letters rearranged gives 'undres'.
'undres'+'s'='UNDRESS'
(Other definitions for undress that I've seen before include "Remove clothes, strip" , "Take off clothing, strip" , "Disrobe - uniform for ordinary occasions" , "Sunders (anag)" , "Divest of clothes" .)