Lest, perhaps, the overhead light proves frightening (8)
I believe the answer is:
startles
'overhead light proves frightening' is the definition.
I can't tell whether this definition defines the answer.
'lest perhaps the' is the wordplay.
I cannot really see how this works, but
an anagram of 'lest' is 'tles' which is located in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'sar' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for startles that I've seen before include "Causes to feel sudden alarm" , "Shocks from starlets" , "Takes by surprise, alarms" , "Frightens suddenly" .)