Hi, I am assuming you mean the most common Eucalyptus sold in the uk, Eucalyptus gunnii, and the answer is yes, it will recover, they can be kept as more of a bush than a tree by regular pruning, this also means that they will retain the juvenile foliage, instead of the long, thin, mature foliage, Derek.

Agree with Derekm - I cut ours to the ground in March because I want to keep it as a shrub rather than a tree - its 6 or 7 feet again by the end of summer.

i agree as well,they are quite used to pruning althogh if uve cut all the leaves or most of the leaves off then let it recover as they will now grow new leave buds,but to be honest i prefer the plant as a tree as it is its natrual growth.