Cultivated my acorn - that's initially meaningful (7)
I believe the answer is:
acronym
'cultivated my acorn that's initially meaningful' is the definition.
I can't tell whether this defines the answer.
'cultivated my acorn that's initially' is the wordplay.
'cultivated' indicates an anagram.
'that's initially' means one lot of letters go next to another.
'my' put after 'acorn' is 'acornmy'.
'acornmy' anagrammed gives 'ACRONYM'.
Can you help me to learn more?
(Other definitions for acronym that I've seen before include "Eg, Nato, Sars" , "A word formed from the initial letters of others" , "Radar, for example" , "eg Ernie; radar" , "radar, for one" .)