Increase of 151 million? Bravo! (5)
I believe the answer is:
climb
'increase' is the definition.
(I know that climb is a more specific form of the action grow)
'151 million? bravo' is the wordplay.
'151' becomes 'CLI' (Roman numerals).
'million?' becomes 'm' (abbreviation).
'bravo' becomes 'b' (phonetic alphabet: alpha, bravo, charlie etc.).
'cli'+'m'+'b'='CLIMB'
'of' acts as a link.
(Other definitions for climb that I've seen before include "Go upwards" , "mountaineer's intent?" , "Get a rise" , "showing the way up" , "What mountaineer does" .)