Stretch a point and look inside (7)
I believe the answer is:
prolong
'stretch' is the definition.
(thesaurus)
'a point and look inside' is the wordplay.
I cannot really see how this works, but
'point' could be 'p' (abbreviation) and 'p' is present in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
'look' could be 'lo' ('lo' is an archaic exclamation meaning 'look!') and 'lo' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for prolong that I've seen before include "Draw out" , "Extend the duration of" , "String out" , "Have extended" , "Spin out" .)