Very large pair regularly exposed in the Sun (5)
I believe the answer is:
solar
'the sun' is the definition.
(I've seen this before)
'very large pair regularly' is the wordplay.
'very' becomes 'so' (both can mean 'extremely').
'large' becomes 'L' (eg in clothes sizes).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternate letters of 'pair' are 'ar'.
'so'+'l'+'ar'='SOLAR'
'exposed in' is the link.
(Other definitions for solar that I've seen before include "like a star" , "type of radiation" , "Particular star's" , "of heavenly body" , "sunny?" .)