Thatcher, for instance, lifted very heavy weight (8)
I believe the answer is:
margaret
'thatcher' is the definition.
(prime minister Margaret Thatcher)
'lifted very heavy weight' is the wordplay.
'lifted' says the letters should be written backwards (going up in down clue).
'very heavy' becomes 'tera' (I can't justify this - if you can you should believe this answer much more).
'weight' becomes 'gram' (unit of weight).
'tera'+'gram'='teragram'
'teragram' in reverse letter order is 'MARGARET'.
'for instance' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for margaret that I've seen before include "Thatcher, perhaps" , "- of Anjou, consort to Henry VI" , "- Rutherford, actress" , "Saint who was queen of Scotland" , "Princess and Thatcher" .)