a pic from tamron 70-300+ macro ..
It looks like you have quite dark lighting conditions with F5.6 and 1 Sec and ISO800.
If you somehow make this much brighter with some extenal lighting or a flash then you could increase the DOF quite a bit by using say F16.This would make some of the out of focus parts "sharper".
The extra light would also allow you to reduce the SS to maybe 1/200 sec and avoid any movement blur caused by camera shake or movement of the critter.
And finally you could also reduce the ISO to minimise the noise in the pic
You could also try sharpening in pp
Good luck. Would be good to see the result.