Small bit of information to lift acceleration (4)
I believe the answer is:
iota
'small bit' is the definition.
(I've seen this in another clue)
'information to lift acceleration' is the wordplay.
'information' becomes 'i' (common abbreviation for information).
'lift' is an anagram indicator (I've seen 'lifts' mean this).
'acceleration' becomes 'a' (symbol used in Physics e.g. f=ma).
'to' with letters rearranged gives 'ot'.
'i'+'ot'+'a'='IOTA'
'of' acts as a link.
(Other definitions for iota that I've seen before include "Jot or tittle" , "Ninthe letter of the Greek alphabet" , "letter from Greece" , "Hint" , "Just a jot, like Greek letter" .)