Heading off, intellectual given to falls? (5)
I believe the answer is:
rainy
'given to falls?' is the definition.
'heading off intellectual' is the wordplay.
'heading off' means to remove the first letter.
'intellectual' becomes 'brainy' (I've seen this before).
'brainy' with its first letter removed is 'RAINY'.
(Other definitions for rainy that I've seen before include "The day one saves for" , "Drizzly" , "Save your money for a . . . . . day - to buy an umbrella?" , "Pluvial" , "Wet, showery" .)