Start to hold calipers turned round and round? (9)
I believe the answer is:
spherical
'round?' is the definition.
('spherical' can be similar in meaning to 'round')
'start to hold calipers turned round' is the wordplay.
'start to' indicates taking the first letters.
'turned' is an anagram indicator.
'round' indicates putting letters inside.
The first letter of 'hold' is 'h'.
'calipers' is an anagram of 'sperical'.
'h' placed within 'sperical' is 'SPHERICAL'.
'and' is the link.
(Other definitions for spherical that I've seen before include "Globular" , "Like a ball" , "As balls" , "Globe-shaped" , "Rotund" .)