Vice chairman initially was the guiding light (5)
I believe the answer is:
clamp
'vice' is the definition.
(I've seen this before)
'chairman initially was the guiding light' is the wordplay.
'initially' suggests taking the first letters.
'was the guiding light' becomes 'lamp' (I can't explain this - if you can you should believe this answer much more).
The initial letter of 'chairman' is 'c'.
'c'+'lamp'='CLAMP'
Can you help me to learn more?
(Other definitions for clamp that I've seen before include "Firmly hold" , "pile of turf" , "Wheel vice" , "Firmly press" , "Gripping tool" .)