State head invests approximately nothing - that might lead to grounds for bitterness (5,4)
I believe the answer is:
cacao bean
'state head invests approximately nothing that might lead to grounds for bitterness' is the definition.
The definition suggests a singular noun which matches the answer.
'state head invests approximately nothing' is the wordplay.
'state' becomes 'ca' (abbreviation for California).
'head' becomes 'bean' (bean is a kind of head).
'invests' means one lot of letters goes inside another (inserted letters are invested).
'approximately' becomes 'ca' (abbreviation for circa).
'nothing' becomes 'O' (looks like zero - 0).
'ca'+'bean'='cabean'
'ca'+'o'='cao'
'cabean' enclosing 'cao' is 'CACAO BEAN'.
Can you help me to learn more?