Light moggy originally in comfortable position? (4)
I believe the answer is:
lamp
'light' is the definition.
(lamp is a kind of light)
'moggy originally in comfortable position?' is the wordplay.
'originally' says to take the initial letters.
'in' indicates putting letters inside.
'comfortable position?' becomes 'lap' (as in sitting on someone's lap).
The first letter of 'moggy' is 'm'.
'm' inserted inside 'lap' is 'LAMP'.
(Other definitions for lamp that I've seen before include "punch" , "Device providing illumination" , "bulb" , "This could be standard" , "Florence Nightingale was the Lady with the . . . ." .)