Be badly upset having criminal bury me outside (9)

'be' is the definition.
('beryllium' can be a synonym of 'be')

'upset having criminal bury me outside' is the wordplay.
'upset' shows that the letters should be reversed in order.
'having' becomes 'ill' (I can't justify this - if you can you should give a lot more credence to this answer).
'criminal' indicates anagramming the letters.
'outside' is an insertion indicator.
'ill' back-to-front is 'lli'.
'bury'+'me'='buryme'
'buryme' anagrammed gives 'beryum'.
'lli' placed within 'beryum' is 'BERYLLIUM'.

'badly' acts as a link.
This may not be correct. It may be part of another bit of the clue.

Can you help me to learn more?