Orchestra pits remodelled to be very high (13)
I believe the answer is:
stratospheric
'be very high' is the definition.
(high up in the air)
'orchestra pits remodelled' is the wordplay.
'remodelled' is an anagram indicator.
'orchestra'+'pits'='orchestrapits'
'orchestrapits' with letters rearranged gives 'STRATOSPHERIC'.
'to' acts as a link.
(Other definitions for stratospheric that I've seen before include "Sky-high (informal)" , "Belonging to the upper air" , "Very high" .)