A sun god in close-up (3)
I believe the answer is:
sol
'a sun god' is the definition.
'Sol' can be an answer for 'god' (Sol is an example). I'm unsure of the 'a sun' bit.
'in close-up' is the wordplay.
'in' says the answer is hidden in the clue.
'up' is a reversal indicator (in down clue: letters go upwards).
'los' is hidden in the letters of 'close'.
'los' backwards is 'SOL'.
Can you help me to learn more?
(Other definitions for sol that I've seen before include "Note; Peruvian currency" , "Personification of the sun" , "Note, old french coin" , "Spanish and poetic sun" , "Roman sun-god" .)