Elevate the core of sun worship (7)
I believe the answer is:
upraise
'elevate' is the definition.
(I've seen this before)
'the core of sun worship' is the wordplay.
'the core of' indicates the central letters.
'worship' becomes 'praise'.
The middle letter of 'sun' is 'u'.
'u'+'praise'='UPRAISE'
(Other definitions for upraise that I've seen before include "EU pairs (anag) - lift higher" , "Erect" , "Exalt - elevate" .)