Small son stops plant growth (7)
I believe the answer is:
blossom
'growth' is the definition.
(I have seen 'attractive growth' mean 'blossom' so perhaps 'growth' could also mean 'blossom')
'small son stops plant' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'son' becomes 's' (genealogical abbreviation for son).
'stops' is an insertion indicator.
'plant' becomes 'bloom' (I can't explain this - if you can you should give a lot more credence to this answer).
's'+'s'='ss'
'ss' inserted into 'bloom' is 'BLOSSOM'.
Can you help me to learn more?
(Other definitions for blossom that I've seen before include "Yield flowers" , "Develop promisingly" , "Thrive" , "Flourish and prosper" , "Mature promisingly" .)